The present inventive concept herein relates to memory devices, and more particularly, to magnetic memory devices.
As electronic devices are expected to operate at higher speeds and lower power consumption, memory devices included in the electronic devices may also be needed to provide faster read/write operation and lower operational voltage. In order to satisfy these requirements, magnetic memory devices are being studied. Since a magnetic memory device may offer high speed operation and/or nonvolatile characteristics, it is a good candidate for next-generation memory.
A magnetic memory device may have a magnetic tunnel junction (MTJ). The magnetic tunnel junction (MTJ) is formed by two magnetic substances and an insulating layer disposed between the two magnetic substances. A resistance of the magnetic tunnel junction (MTJ) may be altered according to the respective magnetization directions of the two magnetic substances. More specifically, when magnetization directions of the two magnetic substances are anti-parallel to each other (e.g. in opposite directions relative to one another), the magnetic tunnel junction (MTJ) has a relatively large or higher resistance, and when magnetization directions of the two magnetic substances are parallel to each other (e.g. in the same direction relative to one another), the magnetic tunnel junction (MTJ) has a relatively small or lower resistance. Data may be written/read based on the difference of resistance. A current density for reversing the magnetization of a free layer of a magnetic memory device is called a critical current density (Jc).